The present invention is related to information visualization, and more particularly to a method and an apparatus for generating a tree map.
A tree map is a tool for data visualization by displaying a hierarchical view of tree-structured data, in the form of nested rectangles. In the prior art, several mature algorithms are available for displaying a tree map, where details may be found at: http://en.wikipedia.org/wiki/Treemapping. Tree maps may be applied to various fields, for example, applicable for making disk space statistics, displaying project progress, and making population statistics etc. It is possible to display in the whole screen a great amount of node information by means of a tree map. Therefore, the overall concept can be well presented, and it is easier to learn how the entirety is divided into parts, for example, it is easy to observe where the space of a disk goes to and where the budget of a company goes to, and so on.
Next, a description is made with a tree map having nested rectangles (other shapes may be adopted, e.g., fan-shape). In a tree map, one area is normally divided into rectangles representing branches of the tree (each branch of the tree is represented by one rectangle). Each rectangle is filled with small rectangles representing its leaf nodes. The rectangle of each leaf node has two different attributes. Normally, the area of the rectangle is proportional to the size of the leaf node, and the color of the rectangle indicates other dimensional information of the leaf node.
FIG. 3C illustrates a tree map display effect drawing of the prior art, from which the overall concept can be obtained, however it is needed to know detailed information of each node, and therefore although sizes of some nodes are very small (e.g., the lower right corner of FIG. 3C), their information cannot be ignored. In the prior art, the most common approach is to observe the small node by zooming-in the block, however if it is desired to observe all the small nodes, many such actions have to be made, which has low efficiency. Especially, such problem of interaction with low efficiency is serious in the prior art when a great amount of small nodes are in a same layer.